It doesn't matter to me at all, I just go with whatever is generally accepted by the mailing list (or perhaps, whatever is generally accepted by the most vocal part of the mailing list). Although, I only ever really did the whole "inline snippets" thing when I'm tearing someone up in a flame war. Most other replies don't require the precision-quoting.
To be honest, what annoys me far more than someone putting a reply in the wrong place is when I get 30 emails from a list that generally provides an average of about 8 a day replying to a guy trolling on about a 20-year-old argument